Modern wireless communication networks are typically placed under great demands to provide high data capacity within the constraints of the allocated signal frequency spectrum. In cellular wireless communication networks, capacity may be increased by re-using frequencies between cells, typically according to a predetermined frequency re-use pattern. A fixed wireless access system may comprise a base station, which may be referred to as an access point, typically mounted on an antenna tower, and a number of subscriber modules installed at customer premises. The area of coverage of an access point may be divided into sectors, each sector being used to transmit and receive with a respective cell. Capacity may be further increased within a cell by steering respective beams towards specific user equipments, which may be referred to as subscriber modules, to allow communication between the access point with improved gain and/or reduced interference reception in comparison with a beam covering a sector. The access point may be equipped with an antenna array and a beamformer for each sector, for forming beams for communication with each respective subscriber module. The beamformer may be required to form beams of various beamwidths in different modes of operation.
It may be a requirement to maintain effective isotropic radiated power (EIRP) within a predetermined limit. This may be achieved by limiting the power transmitted to each antenna element of the antenna array to a level such that, if the worst case maximum array gain were applied by the beamformer, the EIRP limit would not be exceeded. However, this approach has the disadvantage that the access point may be caused to transmit at a level significantly below the EIRP limit for beamformer settings that do not apply the maximum array gain. This may limit the signal to noise ratio achievable on a link and so limit system data capacity.
It is an object of the invention to mitigate the problems of the prior art.